Choose the best offline page when given an online URL.

components/offline_pages/offline_page_model.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 224 matching lines @@
   // This function is deprecated, and may return |nullptr| even if a page
   // exists, depending on the implementation details of OfflinePageModel.
   // Use |GetPageByOfflineURL| instead.
   const OfflinePageItem* MaybeGetPageByOfflineURL(
       const GURL& offline_url) const;
 
   // Returns the offline pages that are stored under |online_url|.
   void GetPagesByOnlineURL(const GURL& online_url,
                            const MultipleOfflinePageItemCallback& callback);
 
+  // Returns via callback an offline page saved for |online_url|, if any. The
+  // best page is chosen based on creation date; a more recently created offline
+  // page will be preferred over an older one. This API function does not
+  // respect namespaces, as it is used to choose which page is rendered in a
+  // tab. Today all namespaces are treated equally for the purposes of this
+  // selection.
+  void GetBestPageForOnlineURL(const GURL& online_url,
+                               const SingleOfflinePageItemCallback callback);
+
   // Returns an offline page saved for |online_url|. A nullptr is returned if
-  // not found.
-  const OfflinePageItem* MaybeGetPageByOnlineURL(const GURL& online_url) const;
+  // not found.  See |GetBestPageForOnlineURL| for selection criteria.
+  const OfflinePageItem* MaybeGetBestPageForOnlineURL(
+      const GURL& online_url) const;
 
   // Checks that all of the offline pages have corresponding offline copies.
   // If a page is discovered to be missing an offline copy, its offline page
   // metadata will be removed and |OfflinePageDeleted| will be sent to model
   // observers.
   void CheckForExternalFileDeletion();
 
   // Reports the storage histograms related to total size of all stored offline
   // pages. Method is to be called after a page was saved or some pages are
   // deleted. In the latter case |reporting_after_delete| is set to true.
@@ skipping 40 matching lines @@
       const MultipleOfflineIdCallback& callback) const;
   void GetPageByOfflineIdWhenLoadDone(
       int64_t offline_id,
       const SingleOfflinePageItemCallback& callback) const;
   void GetPagesByOnlineURLWhenLoadDone(
       const GURL& offline_url,
       const MultipleOfflinePageItemCallback& callback) const;
   void GetPageByOfflineURLWhenLoadDone(
       const GURL& offline_url,
       const SingleOfflinePageItemCallback& callback) const;
+  void GetBestPageForOnlineURLWhenLoadDone(
+      const GURL& online_url,
+      const SingleOfflinePageItemCallback& callback) const;
 
   // Callback for checking whether we have offline pages.
   void HasPagesAfterLoadDone(const std::string& name_space,
                              const HasPagesCallback& callback) const;
 
   // Callback for loading pages from the offline page metadata store.
   void OnLoadDone(const base::TimeTicks& start_time,
                   OfflinePageMetadataStore::LoadStatus load_status,
                   const std::vector<OfflinePageItem>& offline_pages);
 
@@ skipping 90 matching lines @@
   std::unique_ptr<OfflinePageStorageManager> storage_manager_;
 
   base::WeakPtrFactory<OfflinePageModel> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageModel);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_MODEL_H_